Oprah isn’t shy about her love of Spanx. “I love Spanx, I love Spanx. I wear Spanx every single day,” she once said. “I’ve given up panties. I wear Spanx!”

Plenty of other celebrities, including Gwyneth Paltrow, Jennifer Garner, and Tyra Banks, swear by the slimming garments, and Miley Cyrushas even called Spanx “a gift from God.”

However, some doctors warn that Spanx and other shapewear may pose serious health risks, according to a recent piece in the Huffington Post.

First, while shapewear slims your figure, it also squeezes your organs, compressing the stomach, intestine, and colon. This can worsen conditions like acid reflux and heartburn, prevent healthy digestion, place unhealthy pressure on your bladder, and compress your diaphragm, preventing full respiration.

Spanx and other shapewear can also cut off circulation to your legs. “It’s like putting these giant rubber bands around your upper thighs and tightening them when you sit,” chiropractor Dr. Karen Erickson told the Post. Decreased circulation can lead to blood clots and the development of varicose veins, she added.

And in one of the ickier warnings, tight shapewear traps moisture on your skin when you sweat, which can lead to yeast and bacterial infections, including infection of hair follicles (folliculitis), which can be hard to treat.

So while it’s fine to wear Spanx or other shapewear every now and then for a special occasion, Dr. Erickson said it should not be part of your daily wardrobe.

“Everyone I know owns shapewear—it’s kind of a miracle,” she said. “But I think we want to be mindful to not wear it on a day-in and day-out basis.”